Grapefruit is the lighter fruit; orange is the more nutrient-dense one. Per 100 g grapefruit carries 30 calories to an orange’s 47, and less sugar (7 g against 9.4 g). But the orange comes back with more than twice the fibre — 2.4 g against 1.1 g — plus more potassium (181 mg against 127 mg) and more protein.
There is one non-nutritional difference that matters more than any of this: grapefruit interacts with a long list of prescription medicines and oranges do not. If you take anything regularly, that is the deciding factor, not the calorie count.
| Nutrient | Orange | Grapefruit |
|---|---|---|
| Calories | 47 kcal | 30 kcal |
| Protein | 0.94 g ✓ | 0.55 g |
| Total Carbohydrate | 11.75 g | 7.5 g |
| Dietary Fiber | 2.4 g ✓ | 1.1 g |
| Total Sugars | 9.35 g | 6.98 g ✓ |
| Total Fat | 0.12 g | 0.1 g |
| Saturated Fat | 0.02 g | 0.01 g ✓ |
| Sodium | 0 mg | 0 mg |
Notable compounds in each
When to choose each
Reach for oranges for more than double the fibre and more potassium, and because they are the safer choice alongside medication. Reach for grapefruit when you want the lower-calorie, lower-sugar option and a sharper flavour — but check it against anything you have been prescribed first. Both are strong sources of vitamin C.
Orange vs grapefruit nutrition per 100g
Both are the raw fruit without peel. A medium orange is around 130 g and half a grapefruit around 120 g, so a real portion is close to the figures above in both cases — unusually for this site, per 100 g is roughly a serving here.
Juice is a different food from either. Juicing removes most of the fibre while concentrating the sugar, which is why whole fruit and fruit juice are treated differently in dietary advice.
Common questions
Which is healthier, orange or grapefruit? Oranges have more than twice the fibre and more potassium; grapefruit has fewer calories and less sugar. If you take prescription medication, oranges are the safer default because grapefruit interferes with how a number of drugs are metabolised.
Why can’t you eat grapefruit with medication? Compounds in grapefruit block an enzyme in the gut that breaks down many drugs, which can leave far more of the drug in your bloodstream than intended. It affects a long list including some statins, blood pressure drugs and immunosuppressants. Check the leaflet that came with your medicine, or ask a pharmacist — this one is worth asking about rather than guessing.
Does grapefruit have less sugar than orange? Yes — 7 g per 100 g against 9.4 g, and fewer calories with it, 30 against 47.
Is grapefruit good for weight loss? It is low in calories and high in water, which makes it a filling thing to eat for very few calories. The old idea that grapefruit specifically burns fat is not supported; what helps is that it is a bulky, low-calorie food.